1. Field of the Invention
The present invention relates to nematic liquid crystals having advantageous properties which can be obtained from novel chemical substances.
2. Description of the Prior Art
It is well known that within the temperature range from the first melting point to the second melting point, also known as the clarification point, liquid crystals exist in a state of mesomorphism in which they are similar to solid crystals so far as their molecular arrangement and optical properties are concerned. In nematic systems, the elongated molecules have their axes parallel to each other, and their orientation can be controlled by an electric or magnetic field. This property forms the basis of the majority of their applications in the electro-optical and display fields.
Numerous chemical substances are known which will form liquid crystals. These liquid crystals will be more or less stable in terms of time depending upon the particular substance used in their formation. Among the known substances which provide high stability liquid crystals are the tolane derivatives of the formula: ##SPC2##
Wherein R.sub.1 and R.sub.2 signify organic radicals. These compounds suffer the disadvantage that they can only be used as liquid crystals within relatively narrow temperature ranges, which are often located far outside normal temperature ranges. Hence, their field of use has been narrowly limited.
A need continues to exist for a material capable of forming liquid crystals, which will provide a high degree of stability within normal temperature ranges.